From 3b65599768afac5f77e21bf9a528ea2bb004887b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Tue, 24 Oct 2023 00:04:37 +0200
Subject: [PATCH] Add a `NONBLOCKING_QUERY_RESOLVE` downlevel feature

---
 wgpu-hal/src/gles/adapter.rs |  9 ++++++---
 wgpu-types/src/lib.rs        | 17 +++++++++++++++++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/wgpu-hal/src/gles/adapter.rs b/wgpu-hal/src/gles/adapter.rs
index 3e1add825e..888719fd84 100644
--- a/wgpu-hal/src/gles/adapter.rs
+++ b/wgpu-hal/src/gles/adapter.rs
@@ -411,6 +411,11 @@ impl super::Adapter {
             wgt::DownlevelFlags::MULTISAMPLED_SHADING,
             supported((3, 2), (4, 0)) || extensions.contains("OES_sample_variables"),
         );
+        let query_buffers = extensions.contains("GL_ARB_query_buffer_object")
+            || extensions.contains("GL_AMD_query_buffer_object");
+        if query_buffers {
+            downlevel_flags.set(wgt::DownlevelFlags::NONBLOCKING_QUERY_RESOLVE, true);
+        }
 
         let mut features = wgt::Features::empty()
             | wgt::Features::TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES
@@ -450,9 +455,7 @@ impl super::Adapter {
             supported((3, 1), (4, 2)) || extensions.contains("GL_ARB_shader_image_load_store"),
         );
         features.set(wgt::Features::SHADER_UNUSED_VERTEX_OUTPUT, true);
-        let query_buffers = extensions.contains("GL_ARB_query_buffer_object")
-            || extensions.contains("GL_AMD_query_buffer_object");
-        if extensions.contains("GL_ARB_timer_query") && query_buffers {
+        if extensions.contains("GL_ARB_timer_query") {
             features.set(wgt::Features::TIMESTAMP_QUERY, true);
             features.set(wgt::Features::TIMESTAMP_QUERY_INSIDE_PASSES, true);
         }
diff --git a/wgpu-types/src/lib.rs b/wgpu-types/src/lib.rs
index ec968f9e31..82989598ef 100644
--- a/wgpu-types/src/lib.rs
+++ b/wgpu-types/src/lib.rs
@@ -1463,6 +1463,23 @@ bitflags::bitflags! {
         ///
         /// The GLES/WebGL and Vulkan on Android doesn't support this.
         const SURFACE_VIEW_FORMATS = 1 << 21;
+
+        /// If this is true, calls to `CommandEncoder::resolve_query_set` will be performed on the queue timeline.
+        ///
+        /// If this is false, calls to `CommandEncoder::resolve_query_set` will be performed on the device (i.e. cpu) timeline
+        /// and will block that timeline until the query has data. You may work around this limitation by waiting until the submit
+        /// whose queries you are resolving is fully finished (through use of `queue.on_submitted_work_done`) and only
+        /// then submitting the resolve_query_set command. The queries will be guarenteed finished, so will not block.
+        ///
+        /// Supported by:
+        /// - Vulkan,
+        /// - DX12
+        /// - Metal
+        /// - OpenGL 4.4+
+        ///
+        /// Not Supported by:
+        /// - GL ES / WebGL
+        const NONBLOCKING_QUERY_RESOLVE = 1 << 22;
     }
 }